Hydrophobization of metallic surfaces by means of Al2O3-HDTMS coatings

In this work, the structure and wetting behavior of stainless steel coated with sol-gel derived alumina and hexadecyltrimethoxysilane (HDTMS) deposits were studied. As a typical result, an artificial lotus-leaf like corundum structure with a dual nano/micro-scaled roughness was developed at specific deposition and sintering conditions. Water contact angle measurements indicated that the surface functionalization by HDTMS enhances hydrophobicity, where this effect is highlighted when an alumina interlayer is used. In this regard, the most hydrophobicity level was obtained for the surface coated with the lotus-featured alumina and HDTMS coatings. In addition, using dimethylformamide contact angle measurements, the involved interfacial energies were considered to further understand and correlate the surface’s roughness and wetting. In conclusion, the relatively inexpensive and facile method used in this work donates outstanding capabilities to metallic surfaces and provides a new driving force for their further developments.